Related Experiment Video
Updated: Jul 2, 2025
In Vitro Application of a Wireless Sensor in Flexion-Extension Gap Balance of Unicompartmental Knee Arthroplasty
Published on: May 5, 2023
High three-dimensional accuracy of component placement and lower limb alignment using a robotic arm-assisted system
Emanuele Diquattro1, Robert Prill2,3, Mikhail Salzmann2
1Orthopaedic-Traumatology and Prosthetic Surgery and Revisions of Hip and Knee Implants, IRCCS Istituto Ortopedico Rizzoli, Bologna, Italy.
Purpose:
It was hypothesized that robotic arm-assisted total knee arthroplasty (RA-TKA) using additionally a gap-balancing instrumentation will show high accuracy in executing the planning in femoral and tibial component placement throughout the range of knee motion (ROM) during TKA surgery.
Methods:
Prospectively collected data were analysed for patients undergoing RA-TKA. A cruciate retaining cemented design was implanted using the MAKO® robotic system. Lower limb alignment at 0°, 30°, 45°, 60° and 90° of flexion was recorded at the beginning of surgery and finally after implantation of the components. A ligament tensioner was inserted after tibial precut to measure the extension and flexion gap, and final component placement was planned based on 3D CT images. Femoral and tibial component placement was measured in all three planes.
Results:
A total of 104 patients were included (mean age 69.4 ± 9 years; 44 male, 60 female). The difference in component placement after planning and final implantation showed less valgus of 0.7° ± 1.4° (p < 0.001), less external rotation of 0.6° ± 1.9° (p = 0.001) and less flexion of 0.9° ± 1.8° (p < 0.001) for the femoral component. The tibial component was placed in more varus of 0.2° ± 0.9° (p = 0.056) and more posterior slope of 0.5° ± 0.9° (p < 0.001). The lower limb alignment in extension was 4.4° ± 5.2° of varus of the native knee and changed to 1.2° ± 1.9° of varus after TKA (p < 0.01).
Conclusion:
Robotic-assisted TKA helps to achieve the target of alignment and component placement very close to the planning. It allows optimal component placement of off-the-shelf implants respecting patient's specific anatomy.
Level Of Evidence:
Level II.
